I have therefore whereof I may glory through (rather, I have my boasting in) Christ Jesus in the things that pertain unto God ( τὰ πρὸς θεόν—the same phrase as is used in Hebrews 5:1 with reference to priestly service). St. Paul's purpose in this and the four following verses is to allege proof of his being a true apostle with a right to speak with authority to the Gentiles. It is evident, he says, from the extent and success of my apostolic labours, and the power of God that has accompanied them. So also, still more earnestly and at length, in 2 Corinthians 11:1-33. and 12. As to his reason for frequently thus insisting on his true apostleship, and for asserting it in writing to the Romans, see note on Romans 1:1.
For I will not dare to speak of any of those things which Christ hath not wrought through me unto the obedience of the Gentiles (meaning, I will not dare to speak, of any mere doings of my own, but only of those in which the power of Christ working through my ministry has been displayed) by word and deed, by the power of signs and wonders (i.e. displays of miraculous power. It is noteworthy how St. Paul alludes incidentally in his letters to such "signs and wonders" having accompanied his ministry, as to something familiar and acknowledged, so as to suggest the idea of their having been more frequent than we might gather from the Acts of the Apostles. Had the alleged "signs and wonders" been unreal, we might have expected them to be made more of in the subsequent narrative of an admirer than in contemporary letters), by the power of the Spirit of God; so that from Jerusalem, and round about as far as Illyricum, I have fully preached (literally, I have fulfilled) the gospel of Christ. In thus designating the sphere of his ministry the apostle is denoting its local extent, rather than the course he had taken. He had, in fact, preached first at Damascus (Acts 9:20), and afterwards at Jerusalem (Acts 9:29); but he mentions Jerusalem first, as being the original home of the gospel in the East, and, indeed, the first scene of his own preaching in fellowship with the original apostles. Thence he had extended it in various quarters, and carried it into Europe, Illyricum being the western limit so far reached. It is true that there is no mention in the Acts of his having actually visited Illyria. In the journey of Acts 17:1-34. he plainly got no further west than Betted, which is, however, not far off; and he might possibly mean here only to say that he had extended the gospel to the borders of Illyricum, but for the word πεπληρωκέναι, and his seeming to imply afterwards (Acts 17:23) that he had gone as far as he could in those regions, and consequently contemplated a journey to Spain. Hence, the narrative of Acts not being an exhaustive history, it may be supposed that he had on some occasion extended his operations from Macedonia to Illyricum, as he may well have done on his visit to the latter mentioned in Acts 20:1-38. 1-3, where διελθὼν τὰ μέρη ἐκεῖνα allows for a visit into Illyricum.